Question:

The value of $\int \limits \frac {dx}{x^2(x^4+1)^{3/4}}$ is

Updated On: June 02, 2025
  • $\bigg (\frac {x^4+1}{x^4}\bigg )^\frac {1}{4}+ c $
  • $(x^4+1)^\frac {1}{4}+c$
  • $-(x^4+1)^\frac {1}{4}+c$
  • $- \bigg (\frac {x^4+1}{x^4} \bigg )^ \frac {1}{4}+c$
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The Correct Option is D

Solution and Explanation

$\int \limits \frac {dx}{x^2(x^4+1)^{3/4}}= \int \limits \frac {dx}{x^5 \bigg (1+ \frac {1}{x^4} \bigg )^{3/4}} $
put $1+ \frac {1}{x^4}=t^4 \Rightarrow \frac {-4}{x^5}dx=4t^3dt \Rightarrow \frac {dx}{x^5}=-t^3dt$
Hence, the integral becomes
$\int \limits \frac {-t^3dt}{t^3}=- \int \limits dt=-t+c=- \bigg (1+ \frac {1}{x^4} \bigg )^{1/4}+ c$
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JEE Main Notification

Concepts Used:

Methods of Integration

Given below is the list of the different methods of integration that are useful in simplifying integration problems:

Integration by Parts:

 If f(x) and g(x) are two functions and their product is to be integrated, then the formula to integrate f(x).g(x) using by parts method is:

∫f(x).g(x) dx = f(x) ∫g(x) dx − ∫(f′(x) [ ∫g(x) dx)]dx + C

Here f(x) is the first function and g(x) is the second function.

Method of Integration Using Partial Fractions:

The formula to integrate rational functions of the form f(x)/g(x) is:

∫[f(x)/g(x)]dx = ∫[p(x)/q(x)]dx + ∫[r(x)/s(x)]dx

where

f(x)/g(x) = p(x)/q(x) + r(x)/s(x) and

g(x) = q(x).s(x)

Integration by Substitution Method

Hence the formula for integration using the substitution method becomes:

∫g(f(x)) dx = ∫g(u)/h(u) du

Integration by Decomposition

Reverse Chain Rule

This method of integration is used when the integration is of the form ∫g'(f(x)) f'(x) dx. In this case, the integral is given by,

∫g'(f(x)) f'(x) dx = g(f(x)) + C

Integration Using Trigonometric Identities